Method of manufacturing a self-aligning bearing with a deformable inner member

ABSTRACT

A self-aligning bearing assembly comprising an outer member having a concave inner surface and an inner member carried within the outer member and having a convex outer surface generally complementary to the concave inner surface, the inner member being a deformable plastic member, deforming means to vary the tolerance between the inner and outer members.

BACKGROUND OF THE INVENTION

The present invention relates to self-aligning bearings, includingspherical bearings, spherical rod end bearings and the like. Moreparticularly, the present invention relates to self-aligning bearingshaving a deformable plastic inner member which results in a bearingassembly having uniquely low coefficients of friction. Further, thebearing, in accordance with the present invention, may be "adjusted" inthe field without disassembly or significant "down time" of the machineor apparatus with which it is operatively associated.

The self-aligning form of bearing has found wide acceptance in industryand has been used in a multiplicity of applications and in a variety ofenvironments. As with any type of mechanical element, a sphericalbearing will tend to wear at its bearing surfaces over long periods ofoperation. This wear will generally manifest itself in a "loose" fitbetween the inner member and outer member. That is, as the bearingsurfaces defined by the outer surface of the inner member and the innersurface of the outer member wear, tolerance or gap between these twoparts will increase. On many applications, the spherical bearing mayplay a vital role in the various machine elements that might comprise aprocess line or the like. Accordingly, any malfunction of the sphericalbearing will result in a disabling of the process line which could causesignificant economic loss and possible damage to other apparatus ordevice with which the spherical bearing is associated.

There have been attempts to provide a spherical bearing which can bereadily "adjusted" in the field and these attempts have met with onlylimited success.

SUMMARY OF THE INVENTION

It is therefore the primary object of the present invention to provide aself-aligning bearing assembly comprising an outer member having aconcave inner surface and an inner member carried within the outermember and having a convex outer surface generally complementary to theconcave inner surface, the inner member being a deformable plasticmember deforming means to vary the tolerance between the inner and outermembers.

It is another object of the present invention to provide a self-aligningbearing assembly wherein the inner member is provided with a centralbore and said deforming means includes the connecting means operativelyconnecting said inner member to an associated element at its centralbore.

It is still another object of the present invention to provide aself-aligning bearing assembly wherein said connecting means comprises anut and bolt assembly, the shank of said bolt disposed within saidcentral bore, said nut threadably attached to said bolt to operativelyconnect said inner member to said associated element, the degree ofdeformation of said plastic member depending upon the torque applied tosaid nut.

It is yet another object of the present invention to provide aself-aligning bearing asseembly wherein said inner member is providedwith an opening therethrough, a conical bushing disposed within saidinner member at each open end of said opening.

It is a further object of the present invention to provide aself-aligning bearing assembly wherein there is provided within saidopening a centrally disposed gap between each of said bushings abuttingsaid rib.

It is still another object of the present invention to provide aself-aligning bearing assembly wherein the inner surface of saidbushings define a central bore through said inner member.

It is still a further object of the present invention to provide aself-aligning bearing assembly wherein the conical bushings are moldedin place in said inner member.

It is yet a further object of the present invention to provide aself-aligning bearing assembly wherein said conical bushings are eachfitted within complementary conical depressions formed at each end ofthe inner member.

It is a further object of the present invention to provide aself-aligning bearing assembly wherein said inner member is operativelyconnected to an associated element by a nut and bolt assembly, the shankof said bolt disposed within said opening, said nut threadably attachedto said bolt, the said head of said bolt and the nut effecting thedeforming force on said inner member through said conical bushings, thevectors of said force applied to said bushing to deform said innermember uniformly such that its convex outer surface remainssubstantially spherical.

It is also a further object of the present invention to provide aself-aligning bearing assembly wherein said inner member is manufacturedfrom a self-lubricating plastic material.

It is yet another object of the present invention to provide aself-aligning bearing assembly having a deformable plastic inner memberwhich is elemental in design and inexpensive to manufacture.

It is a further object of the present invention to provide aself-aligning bearing assembly having a deformable plastic inner memberwhich can be manufactured using automated high volume techniques.

Still other objects, features and attendant advantages of the presentinvention will become apparent to those skilled in the art from areading of the following detailed description of the preferredembodiments constructed in accordance therewith, taken in conjunctionwith the accompanying drawings wherein like numerals designate likeparts in the several figures.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side sectional view in elevation of a rod end sphericalbearing in an assembled state and in accordance with the presentinvention;

FIG. 2 is a front elevational view of the bearing of FIG. 1;

FIG. 3 is a side sectional view in elevation of a spherical bearing inan assembled state and in accordance with the present invention;

FIG. 4 is a front elevational view of the bearing of FIG. 3;

FIG. 5 is a side sectional view in elevation of a rod end sphericalbearing in an assembled state and in accordance with another embodimentof the present invention;

FIG. 6 is a front elevational view of the bearing of FIG. 5.

DESCRIPTION OF THE INVENTION

Referring now to the figures and, in particular, FIGS. 1 and 2, there isshown a rod end spherical bearing 10 in its assembled state andpartially sectioned (FIG. 1).

The rod end spherical bearing 10 is configured generally the same as rodend spherical bearings found in the prior art. That is, the rod endspherical bearing 10 comprises an outer member 12 and an inner member14. The outer member 12 is provided with a concave inner surface 16. Theconcave inner surface 16 of the outer member 12 is generallycomplementary to the convex outer surface 18 of the inner member 14. Theinner member 14 is provided with a central bore 20. The outer member 12is provided with a rod end extension 22. The central bore 20 and the rodend extension 22 provide the means by which the rod end sphericalbearing 10 is operatively attached to an associated machine element,apparatus or device. The rod end spherical bearing 10 of FIGS. 1 and 2is of the female variety, that is, the rod end extension 22 isinternally bored and threaded (not shown) and, accordingly, may bethreadably attached to an appropriate male threaded machine element orthe like. Similarly, a connecting means may be placed within the innermember 14 at its central bore 20 to effect operative attachment of theinner member to some associated machine element, apparatus or device.Typically, the connecting means will comprise some suitable form of nutand bolt assembly (not shown). The nut head typically will abut the endsurface 24 of the inner member and the shank of the bolt will passthrough the inner member 14 and, in particular, through the central bore20. The nut which is typically threaded on the bolt will complete theoperative attachment of the inner member to its associated machineelement, etc. Accordingly, it can be seen that the nut and boltarrangement effect a compressive force on the inner member 14. It is atthis juncture that the present invention can best be understood for theinner member as shown in FIGS. 1 and 2 is of a deformable plasticmaterial such as Delrin and Teflon, trademarks of Du Pont. The innermember 14, because of its deformable properties, may be adjusted or,more specifically, the bearing tolerance between the inner member 14 andthe outer member 12 at their respective bearing surfaces (i.e., convexouter surface 18 and concave inner surface 16) may be changed. Thistolerance can be changed by varying the compressive force on thedeformable inner member 14. It can be seen therefore that increases inbearing tolerances caused, for example, by operational wear, can becompensated for by deforming the inner member. For example, all thatwould be required to decrease the tolerance between the inner member 14and outer member 12 would be to tighten the aforementioned nut whichoperatively attaches the inner member to its associated machine element,apparatus or device. As the nut is threadably tightened on theconnecting bolt, the compressive force exerted on the inner member willcause the inner member 14 to reduce its axial dimension and expandproportionately in a radial direction. This radial expansion will tendto reduce the gap or tolerance between the inner member 14 and the outermember 12. A mechanic therefore, by using a suitable wrench or otherform of tool, could suitably adjust the rod end spherical bearing 10 inthe field in its assembled state within an associated machine element,apparatus or device. Consequently, only a minimum amount of down timewould be encountered and further, through proper maintenance eachbearing could be "felt" to determine if adjustment was needed.

The spherical bearing 26 of FIGS. 3 and 4 are denoted by the samenumerals as those in FIGS. 1 and 2 where applicable. The majordistinction of the bearing of FIGS. 3 and 4 is that it is a sphericalbearing and it is not provided with a rod end extension. The innermember 14 is connected or operatively attached to its associated machineelement, apparatus or device in a manner similar to the rod endspherical bearing 10 of FIGS. 1 and 2. However, the outer member 28 isprovided with an outer cylindrical surface 30. It is this outercylindrical surface which is typically used to operatively attach theouter member 28 to its associated machine element, apparatus or device.Accordingly, the spherical bearing of FIGS. 3 and 4 are provided withthe same unique characteristics as the rod end spherical bearing 10which includes the provision of the deformable plastic inner member 14.

Referring now to FIGS. 5 and 6, there is shown another rod end sphericalbearing 32 which embodies another form of the present invention. FIG. 5shows the rod end spherical bearing 32 in its assembled state andpartially sectioned while FIG. 6 shows a side elevational view of thebearing of FIG. 5.

The rod end spherical bearing 32 is provided with an outer member 34whose configuration generally conforms to those found in the prior art.The outer member 34 is provided with a concave inner surface 36. Thisconcave inner surface 36 of the outer member 34 is generallycomplementary to the convex outer surface 38 of the inner member 40. Theinner member 40 is provided with a central bore 42. The outer member 34is provided with a rod end extension 44. The central bore 42 and the rodend extension 44 provides the means by which the rod end sphericalbearing 32 is operatively attached to an associated machine element,apparatus or device.

The rod end spherical bearing 32 of FIGS. 5 and 6 is of the femalevariety, that is the rod end extension 44 in integrally bored andthreaded (not shown) and, accordingly, may be threadably attached to anappropriate male threaded machine element or the like. Similarly, aconnection means may be placed within the inner member 40 and itscentral bore 42 to effect operative attachment of the inner member tosome other associated machine element, apparatus of device, Typically,the connecting means, as with the before mentioned rod end sphericalbearing 10 and spherical bearing 26, will comprise some suitable form ofnut and bolt assembly (not shown). The nut head typically will abut theend surface 46 of the inner member and the shank of the bolt will passthrough the inner member 40 and, in particular, through the central bore42. The nut, which is typically threaded on the bolt, will complete theoperative attachment of the inner member to its associated machineelement, etc. Again, as with the before mentioned rod end spherical 10and spherical bearing 26, it can be seen that the nut and boltarrangement effect a compressive force on the inner member 40. It is atthis juncture that the bearing of FIGS. 5 and 6 is best distinguishedover the rod end spherical bearing 10 and spherical bearing 26. Inparticular, the inner member 40 of the rod end spherical bearing 32 is acomposite structure having generally three elements or parts. The innermember 40 is provided with two conically configured openings 48 at eachopen end thereof. The conical openings 48 smoothly merge one into theother. The conical openings 48 are adapted to receive the conicalbushing 52, that is, in each conical opening there is therein disposedthe conical bushing 52. It can be seen from the figures and, inparticular, FIG. 5 that the central bore 42 of the inner member 40 isdefined by the inner surface of the conical bushings 52. It can also beseen that there is an annular gap 50 between the bushings 52. The convexouter surface 38 of the inner member 40 is defined entirely by thedeformable plastic portion 54 of the inner member 40.

It should be noted at this point that the conical bushings 52 may besimply inserted within each of the conical openings 48 or,alternatively, may be molded in place when the inner member 40 ismanufactured.

The inner member 40 and, in particular, the plastic portion 54 of theinner member 40 has deformable properties and characteristics similar tothe deformable properties of the inner member 14 of the rod endspherical bearing 10. However, the deformable properties of the innermember 40 are more directionalized. The inner member 40 may be adjustedas to the before mentioned inner members by varying the compressiveforce on the deformable inner member by threadably tightening the nut onthe connecting bolt. As the bolt is further tightened, the bushings 52will be forced inwardly towards each other, reducing the axial width ofthe gap 50, and there will be an increase in this compressive forcewhich will tend to reduce the axial dimension of the inner member 40 andexpand it proportionately in a radial direction. The radial expansion ofthe inner member 40 will be somewhat more uniform than the radialexpansion of the inner member 14 under similar circumstances. Morespecifically, as the compressive force is exerted on each of the conicalbushings 52 at their respective end surfaces 46, the vectors of suchforce will radiate angularly and outwardly in a direction toward theconvex outer surface 38. This radiating of the force vectors causes theconvex outer surface to remain substantially spherical even as thecompressive force is increased.

The conical bushings 52 may be manufactured from a wide range ofsuitable materials such as brass and steel. The plastic portion 54 ofthe inner member 40 may be manufactured from the same material that theinner member 14 of the rod end spherical bearing 10 was manufactured,that is, Delrin, Teflon, or the like.

Referring again to the rod end spherical bearing 10 of FIGS. 1 and 2, itshould be appreciated that it can be manufactured using new and uniquetechniques as well as certain tried and tested prior art techniques.With respect to the latter technique, that is, prior art technique, theouter member 12 may be compressed uniformly around the inner member tocomplete the spherical bearing assembly as therein depicted. However, adeparture from the prior art includes the deforming of the inner member14 within a tapered die or the like (not shown) such that the diameterof the convex outer surface 18 is reduced dimensionally to enable theinsertion of the inner member 14 within the outer member 12. Thereafter,the inner member 14 would be released to its natural state and wouldspring to its original dimension to be operatively supported within theouter member 12 at its concave inner surface 16. This unique method mayalso be applied to the spherical bearing 26 of FIGS. 3 and 4. Anadditional element of uniqueness may be included in the method ofassembling the bearings of FIGS. 5 and 6. It can be seen that theplastic portion 54 with the conical bushings removed is even moredeformable inwardly than the inner member 14 of the rod end sphericalbearing 10 and spherical bearing 26. Accordingly, the plastic portion 54may be, by the use of a tapered die, formed in a fashion as before notedwith respect to the inner member 14 and once operatively in place withinthe outer member 34 can be further assembled by the insertion of theconical bushing in the conical openings 48.

Obviously, the present invention is not limited to the specific detailsas herein described, but is capable of other modifications and changeswithout departing from the spirit and scope of the appended claims.

I claim:
 1. A method of manufacturing a self-aligning bearing comprisingthe steps of preforming an outer member having a spherical concave innersurface, preforming an inner member having a convex spherical outersurface generally complementary to said concave inner surface, andproviding said inner member with an opening therethrough, said openingbeing in the form of an outwardly divergent conical depression formed ateach end of said inner member, said inner member being a deformableplastic member, deforming said plastic member inwardly such that thediameter of the convex outer surface of said inner member is reduceddimensionally, inserting said inner member within said outer member,releasing said inner member such that it regains its original dimensionwhereby it is operatively supported within said outer member at saidouter member's concave inner surface.
 2. A method of manufacturing aself-aligning bearing in accordance with claim 1 wherein said methodincludes the additional step of inserting an inwardly convergent conicalbushing in each said conical depression after releasing said innermember within said outer member.
 3. A method of manufacturing aself-aligning bearing in accordance with claim 1 wherein the deformingof said inner member includes placing and pushing said inner memberwithin and through a tapered die.